Marine areas - Whitefish 2025

Published 13 Oct 2026

The European whitefish (Coregonus lavaretus) fishery in the Finnish coastal areas targets mainly the anadromous ecotype and to a lesser extent also the sea-spawning ecotype. Commercial whitefish catches in coastal areas have shown a long-term declining trend. However, in the past two years the catches have slightly increased, from the lowest level recorded in 2023. The most recent data on recreational whitefish catches, based on survey results, are from 2024.

The long-term decline in whitefish catches results from not only the lower numbers of individuals available for fishing, but also from the lower capacity of the gillnet fishery, which, in turn, is partly due to strengthening seal populations that interfere especially with the whitefish gillnet fishery. Catches in the recreational fishery have in recent years been of the same order of magnitude as commercial catches.

Whitefish catches from fish traps and gillnets vary locally, with the catch share of fish traps increasing slightly in recent years. Unit gillnet catches have remained at relatively constant levels since the turn of the millennium. The main season for the whitefish fishery is the open water period, between early May and late October, with the catch reports peaking in September and October, and in the Bothnian Bay also in June.

Two different whitefish ecotypes that live in the Finnish coastal areas differ in their reproductive behaviour: the anadromous ecotype migrates to spawn in coastal rivers, while the sea-spawning ecotype remains in the sea for spawning. Sea-spawning whitefish tend to have more localised ranges, and their catches have generally remained at sustainable levels, as indicated by the age distribution of the individuals caught. Its catch levels have predominantly remained sustainable, as judged by the age distribution of the catch (Veneranta et al. 2025). The catches of the anadromous ecotype, in turn, rely mainly on stocking programmes, while its natural reproduction is very weak, except in in the Torne (and to some extent Simojoki). Most anadromous whitefish are caught before concluding their first spawning migration. Indeed, the anadromous whitefish individuals are nowadays caught younger than in previous decades. Presumably, such intense fishing pressure is one of the factors that has changed the body size distributions in whitefish populations (Heikinheimo & Mikkola, 2004). The average size of anadromous whitefish entering the coastal rivers of the Bothnian Bay has also decreased over the decades.

The anadromous (i.e. migratory) ecotype constitutes roughly half of the commercial whitefish catch in the Bothnian Bay and most of the catch further south on the coast. The share of the sea-spawning whitefish has increased in the last couple of decades, especially in the Bothnian Bay. This pattern has been influenced by the decline in the anadromous whitefish catches, while the catches of the sea-spawning ecotype have remained stable. A gillnet fishery study in the Kvarken area (Lehtonen et al. 2026) found that the ecotype catch shares can be influenced by the fishing depth, the choice of the fishing season and gillnet mesh size. However, the study also showed that many whitefish individuals cannot be reliably categorised into these two ecotypes.

Since 2024, the minimum permitted mesh size in the whitefish fishery has been 45 mm (knot-to-knot), except for the fishing of sea-spawning whitefish in the Kvarken and Bothnian Bay. By increasing the minimum mesh size, the average size and age of anadromous whitefish are expected to slightly increase in the oncoming few years. These changes may also have a positive effect on the Torne, which in one of the last remaining rivers in Finland where anadromous migratory whitefish are able to reproduce mostly or entirely naturally. However, assessing the consequences of the regulation changes is challenging because the whitefish catches in coastal areas consist of several different stocks, the anadromous ecotype migrates extensively along the coast, the fishery uses a wide variety of different fishing methods, and any changes in population structure typically take place relatively slowly.

References

Heikinheimo, O. & Mikkola, J. 2004. Effect of selective gill-net fishing on the length distribution of European whitefish (Coregonus lavaretus) in the Gulf of Finland. Ann. Zool. Fennici 41: 357–366.

Kallio-Nyberg, I., Veneranta, L. Jokikokko, E. & Leskelä, A. 2020. Vaellussiian pituus- ja ikäjakauma Pohjanlahden saaliissa 1981–2017 sekä 2013 alkaneen verkkokalastussäätelyn vaikutus siikakantoihin. Luonnonvara- ja biotalouden tutkimus 95/2020. Luonnonvarakeskus. Helsinki. 44 s.

Lehtonen, H. 1981. Biology and stock assessments of Coregonids by the Baltic coast of Finland. Finnish Fish. Res. 3: 31–83.

Lehtonen, T.K., Veneranta, L., Bitz O., Fischer, D., Tapio, M. & Leinonen, T. 2026. Challenges in mixed-stock fishery management: The case of the European whitefish in Kvarken, northern Baltic Sea. Fish. Res. 293: 107648.

Leinonen, T. Kallio-Nyberg, I., Koljonen, M.-L., Veneranta, L. & Jokikokko, E. 2020. Pohjanlahden siikakantojen vaelluserot ja ikäluokkien kokoerot: Siikakantojen ekologisten ominaisuuksien tutkimus geneettisen kannantunnistuksen avulla. Luonnonvara- ja biotalouden tutkimus 51/2020. Luonnonvarakeskus. Helsinki. 31 s.

Veneranta, L., Lehtonen, T., Leinonen, T., Harjunpää, H. & Långnabba, A. 2025. Merikutuisen siian verkkokalastuksen säätely Merenkurkussa. Luonnonvara- ja biotalouden tutkimus 77/2025. Luonnonvarakeskus. Helsinki. 37 s.